This program's initial work on laser microsurgical techniques centered on ophthalmological applications (pulsed carbon dioxide lasers and pulsed ND:YAG slit lamp-based laser systems) . Its primary focus for the last six years, however, has been in cardiological applications, in particular laser angioplasty and the development of pulsed, solid-state infrared lasers for microsurgery. We have studied the feasibility of transmission through flexible fiber optics and the effects of excimer lasers and pulsed-dye lasers on tissue, along with acoustic transients and ablation efficiency with increasing pulse fluence. New IR laser sources have been developed (in conjunction with the Naval Research Lab and Quantronix Corp.) which utilize strong water absorption and can be transmitted through low-loss, cladded optical fibers. A collaboration with MCM Labs has led to clinical trials of peripheral (and, more recently, coronary) laser angioplasty, using either a pulsed-dye laser or pulsed infrared lasers with computer-controlled fluorescence guidance. Application of our infrared lasers (particularly the Tm:YAG and silica optical fibers) to laser angioplasty systems is proceeding, with parallel development of a clinical infrared version of the fluorescence guidance system, using a new intravascular ultrasound catheter. Recent work has involved identification of the tissue and biological effects of pulsed lasers, in particular acoustic transients and transient, moderate (approximately 60 degrees C) thermal elevations, and the understanding of clinical results with laser angioplasty.